JPS6115791B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic welding device, and more particularly to a welding machine for sealingly welding a plug to a tube of a steam generator in a nuclear power plant.

The above plugs are placed in leakage pipes on the primary side of steam generators, where radioactivity levels are high enough to limit the amount of time workers can stay inside. One of the particularly important considerations when working in a radioactive environment is the judicious use of human resources. The purpose is to minimize the radiation dose each worker is exposed to.
It is the most effective use of human resources. This is especially important when the worker is a skilled technician, such as a qualified welder. When radiation levels are high, the process of welding a plug to a tubesheet exposes a qualified welder to a defined amount of radiation. The apparatus described herein allows a qualified welder to set the appropriate parameters for the welding torch and plug from outside the radioactive environment. The plug and shaft are removed from the welding equipment, allowing an unskilled worker with limited training time, in a radioactive environment, to place the plug into the appropriate tube and quickly install the welding equipment therein. The sealing weld can then be performed remotely by a qualified welder. The welding equipment described herein not only reduces the amount of time a worker is exposed to radiation during each weld, but also virtually eliminates all exposure to qualified and experienced welders, thereby increasing the welder's usefulness and productivity. Improve your sexuality. Also, less trained and unskilled workers could be used to perform the welding process, greatly increasing the number of available workers, each of whom would safely receive an acceptable amount of radiation. .

JP-A-53-110120 and JP-A-53-110937 by the same applicant as the present application are provided in the head of a steam generator and can be actuated against a pipe end within a part of the head. Discloses an apparatus for positioning a tool from a distance. The tool is remotely operated to insert the plug into the leak tube and seal weld it to the tube. Since the time required to set the tool inside the head of the steam generator is considerable, these tools are useful when there are a large number of pipes to be plugged.

U.S. Pat. No. 4,004,125 describes a multihead welding gun for sealing welding multiple tubes to a tubesheet, but does not disclose a removable shaft that can be attached to a plug.

To summarize the invention, in general, a welding device for a tapered plug having an axial bore that is brought into retention with the end of a tube, when constructed in accordance with the invention, includes a main body and a a removable engagement that rotatably cooperates and is adapted to fit within the axial bore of the plug and is retained within the axial bore in axial alignment with the plug; means for rotating with said body about the axis of said shaft to create a weld surrounding the joint of said tube end and plug with a shaft about which said body is rotatably mounted; a welding torch mounted on the main body and having a welding electrode near the periphery of the plug, the welding device further comprising: rotating the main body together with the welding torch around the plug; and a drive body mounted on the main body and having a drive shaft that engages with or forms the shaft. The welding device can thus weld a plug in one tube and then quickly move on to another tapered plug that has been brought into retention with another tube.

Objects and advantages of the invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.

1, 2 and 5, a welding device 1 is shown for automatically sealing welding a plug 3 into a leakage pipe 5 disposed in a hole 6 in a tube plate 7. ing.

The welding device 1 includes a main body 9, an electric motor 11 suspended on the main body 9, and a welding torch 13 pivotally attached to the main body 9. The welding torch 13 has a main body 15
, a tungsten electrode 17 , and a ceramic cap 19 surrounding the electrode 17 .
forms a nozzle that directs the inert gas supplied to the cap so as to cover the weld pool formed when a current is applied to the tungsten electrode 17. The mounting bracket 21 is pivotally mounted to the body 9 so that it can be fixed in any predetermined angular position, and the torch body 15 is slidable within the bracket 21 in such a way that it can be fixed in any sliding position within the bracket. It is located in Round head screw with hole 2
3 or other fastening means to attach the bracket 2.
1 and the body 15 of the torch 13 can be fixed with respect to the welding device 1 .

The body 9 and the electric motor 11 have a receiving hole 25 suitable for receiving a shaft 27 .

As best shown in FIG. 3, the shaft 27 is a round bar with an external thread 29 at one end, and the other end 30 is tapered to fit into a hole 25 in the motor 11. That is, in this embodiment, the shaft 27 serves as the output shaft or drive shaft of the motor 11, which is a driving body. A central portion 31 (large diameter portion) of the shaft 27 has an opposing flat portion 33 that will receive a wrench (not shown).
has. A circumferential groove 35 is provided near the small diameter end 30 , and a circumferential groove 35 is provided near the small diameter end 30 .
A continuous flat portion 37 is machined. Further, the shaft 27 has a small diameter portion 39 disposed between the male thread 29 and the central portion 31.

The hole 25 in the body 9 has a protrusion 41 which engages a flat part 37 on the shaft 27 to fix the drive shaft of the motor 11 to the shaft 27. A sliding plate 43 is slidably provided within the main body 9 and is biased toward the hole 25 by a spring 45 .
The end 47 of the slide plate 43 is moon-shaped and extends into the hole 25. The moon-shaped end 47 engages the circumferential groove 35 in the shaft 27 and the flat part 3 engages the protrusion 41.
7 and the shaft 27 is installed in the welding device 1. A pin 48 is received within the slide plate 43 and a notch 49 is provided in the body 9 to limit the movement of the slide plate 43 and to bias the slide plate 43 towards the hole 25. 45 creates a working surface.

The main body 9 has a pair of ears 50 disposed on one side thereof. Inside these ear parts 50 is a lever 5.
1 is pivotally mounted by a pin 52. Furthermore, the lever 51 is pivotally connected to the hole 53 of the slide plate 43 in such a manner that when pressed, the slide plate 43 moves away from the shaft 27 and the hole 25, releasing the shaft 27 from the welding device. , the shaft 27 can be easily removed from the welding device 1.

As best shown in Figure 4, the plug 3 is generally cylindrical with steps 57, 58 and 59 rising outwardly from the tip. The plug 3 has an axial bore or bore 61 extending inwardly from the rear end, the bore 61
There is an internal thread 63 at the bottom end. Further, the perforation 61 has two countersink holes, one countersink hole 65 is located near the female thread 63 and has a diameter slightly smaller than the diameter of its main part, and the other countersunk hole 67 is located near the rear end, A thin wall portion 68 is formed near the rear end of the plug 3 for welding the plug 3 to the tube sheet 7. The pipe 5 is drilled to create a press fit with the plug 3.

Therefore, as can be understood from the above description, in the first preferred embodiment of the present invention shown in FIGS. The plug 3 has means for releasably engaging the male thread 63 of the plug 3 such that the plug 3 is held in the bore 61 in an aligned state, that is, the male thread 29. Also,
The welding device 1 includes a motor 11 which is mounted on the body 9 and has a drive shaft forming an axis 27 in order to rotate the body 9 together with the welding torch 13 around the plug 3 .

The welding device 1 operates as follows. axis 27
into the hole 25 in the welding device 1. Lever 5
1 to allow the protrusion 4 to engage the flat part 37. Thereafter, the lever 51 is released to allow the moon-shaped end 47 of the slide plate 43 to engage in the circumferential groove 35, locking the shaft 27 immovably within the welding device 1. The plug 3 threadably engages the outside of the shaft 27, but the engagement can take place before or after the shaft 27 is inserted into the hole 25. However, the plug must be tightly tightened to secure the shaft relative to the plug. Shaft 27 and plug 3
Once set in place, the position of the torch 13 is adjusted by a qualified welder. Welders use round head screws 23
Set the position of the torch 13 with respect to the outer edge 46 of the plug 3 by loosening and moving the torch 13 and/or the mounting bracket 21 as desired to properly align the torch 13 and once aligned. To create a good weld when the plug 3 is inserted into the reamed hole, the torch 13 and mounting bracket 21 are set and secured in position by tightening the round head screw 23. Lever 5
1 again and move the sliding plate 43 to its moon-shaped end 47.
The shaft 27 is moved so that it escapes from the circumferential groove 35.
is released from the above-mentioned immobile state, so that the shaft 27 can then be removed together with the plug 3 from the welding device. The unskilled worker takes the plug 3 with the shaft 27 attached, inserts them into the hole in the tube to be closed, and inserts the plug. In the case of plug force-fit retention, the plug 3 is pressed into the hole in the tube, and the unskilled worker then presses down on the lever 51 with respect to the welding device and aligns the welding device with respect to the axis 27, pushing the lever 51 down. Separate welding equipment 1
is locked about the shaft 27. That is, welding torch 1
3 and the main body 9 that supports the motor 11 and the like are attached to the shaft 27. Thereafter, a qualified welder can remotely control the welding equipment to weld the plug 3 to the pipe 5. When the weld is completed, the unskilled worker should press lever 51.
Remove the welding device from the shaft by pressing down, unscrew the shaft 27 from the plug 3 by unscrewing it using a wrench against the flat 33, and continue this operation until all leakage pipes are closed. Since a qualified welder can assemble the plug 3, shaft 27 and welding device 1 outside the radioactive environment to create a good weld, the qualified welder will not be exposed to radiation inside the steam generator vessel. I don't receive it. When an unskilled worker has been exposed to an acceptable amount of radiation, he is replaced by another unskilled worker. Unskilled personnel require minimal training for the operations that must be performed within the radioactive container.

FIG. 6 shows a further welding device 1' for welding a plug 3 into a tube 5. The welding device 1' is a substrate 71
and a mandrel 7 that is inserted into the pipe and expanded to a state where it is held in place by turning the handle 75.
3. Substrate 71 is positioned near the end of the tube by a stop 76 associated with mandrel 73. A motor 77 is arranged on one side of the substrate 71, and a shaft 79 and a torch 81 are used from the other side. The shaft 79 has a shoulder 83 that contacts the plug 3;
Fix plug 3 with respect to Torch 81 is connected to shaft 7
9 allows the welder to set the proper position of the torch 81 to create a good weld between the plug 3 and the tube 5. Since shaft 79 and torch 81 work together and are biased toward the tubesheet, whenever the shaft moves, the torch moves a similar distance relative to the tubesheet.

Belt 93 and pulley 95 form a driver that transmits rotational movement from motor 77 to torch 81 . The drive body also has a drive shaft (not shown) that engages shaft 79, as will be obvious to those skilled in the art.

Accordingly, in a second embodiment of the invention shown in FIG. 6, the shaft 79 supported by the base plate 71 is attached to and removed from the plug 3 such that it is retained in the borehole in axial alignment with the plug 3. It has a freely engaging portion or shoulder 83. The welding device 1' also includes a drive body (motor 77, belt 93, pulley 95) connected to the welding torch 81 and supported by the substrate 71 to rotate the electrode around the plug 3. .

The welding device 1' as shown in FIG. 6 operates as follows. The plug 3 is placed on the shaft 79 against the shoulder 83 and the torch 81 is adjusted by a qualified welder outside the steam generator vessel and away from the radioactive environment. The welder sets the torch relative to the plug to create a good weld. The plug is removed from the shaft and an unskilled worker enters the radioactive environment or container with the plug and welding equipment in such a way that the plug 3 retains itself within the tube 5.
Insert the plug into the pre-prepared pipe hole near the partition plate or channel head. Insert the inflatable mandrel 73 into the nearby tube 5 and insert the shaft 79 into the plug 3. Push the welding device 1' towards the tube sheet until the stop 76 contacts the tube sheet. axis 79 taking into account the positional variations of the plug 3 with respect to the tube sheet.
The shaft 79 is retained in the plug by a spring biasing the torch 81 toward the tubesheet. Turn the handle 75 until the torch 81 and shaft 79 are in the proper position to form a good weld with respect to the plug.
At the same time, the welding device 1' is held against the tube sheet.
That is, the substrate 71 that supports the torch 81, the driver, and the shaft 79 is attached to the tube 5. After that, the welder energizes the torch 81 and motor 77 to close the plug 3.
Create a sealing weld between the pipe and the pipe. handle 75
If you turn the mandrel 73 from the tube 5,
The welding device can be removed and taken out of the radioactive environment so that a qualified welder can install another plug and continue the operation described above.

The welding equipment described above has the advantage of allowing the use of unskilled personnel to enter the radioactive environment, allowing them to perform the work necessary to produce a good weld with a minimum amount of training, while skilled welders Because the technicians do all their work outside of the radioactive environment, there is no need for a large number of qualified welders when there are many pipes to plug.

In addition, by using the above-described welding device of the present invention, in addition to realizing effective use of human resources, it is possible to reduce the distance between the welding device and the pipe and the plug to be welded without requiring large and powerful equipment. Movements are easily avoided, yet proper positioning of the welding torch is achieved.

[Brief explanation of the drawing]

Figure 1 is a plan view of an apparatus for automatically sealing welding plugs to pipes, Figure 2 is an elevational view, partially in section, of the apparatus of Figure 1, and Figure 3 is an elevational view of the shaft for this apparatus. side view,
FIG. 4 is a cross-sectional view of a plug for use with this device; FIG. 5 is an elevational view of the device and the plug inserted into the tube; and FIG. 6 is an elevational view of another device for sealing welding the plug to the tube. It is a front view. 1... Welding device, 1'... Welding device, 3... Plug, 5... Pipe, 9... Main body, 11... Drive body (motor), 13... Welding torch, 17... Electrode,
27... Shaft, 29... Engaging means (male thread), 61
... shaft hole (drilling), 71 ... board, 77 ... motor, 79 ... shaft, 81 ... welding torch, 83 ...
Engagement means (shoulder), 93...belt, 95...pulley.

Claims (1)

[Claims] 1. A welding device for a tapered plug having an axial hole held in a state of retention with an end of a pipe, the welding device cooperating rotatably with respect to the body and the plug The plug is adapted to fit into the shaft hole of the main body, and has a removable engagement means so as to be held in the shaft hole in an axially aligned state with the plug, a shaft that is rotatably mounted about the axis, and a weld that surrounds the joint of the end of the tube and the plug, and is mounted to the body so as to be rotatable together with the body about the axis of the shaft; and a welding torch having a welding electrode near the periphery of the plug, and the welding device is further attached to the main body to rotate the main body together with the welding torch around the plug. and a drive body having a drive shaft that engages or forms the shaft.